Heart Failure 3, Causes of left ventricular failure

so in this video on heart failure were thinking about the causes of heart failure the etiology and in the stage you don't have the area so what causes heart failure and we're going to start off by thinking about what causes left-sided heart failure so just to remind ourselves we have the diagram that you'll be familiar with from the last video hopefully this is the left side of the heart here this is the left side that's the left and that's the right side here I've got a space so what we have is this is the left heart this is the right heart and of course it's the left heart that's pumping blood to the body so what we have here is we have the left ventricle the aorta taking blood to the body the blood draining back in the systemic veins by the inferior and superior vena cava here we have the pulmonary arteries taking blood from the right ventricle to the lungs draining back line the pulmonary veins to the left atrium so let's think about the causes of a left ventricular failure first of all so we've already learned that heart failure is an inability of the heart to generate sufficient cardiac output to meet the metabolic demands of the tissues so first of all we want to think about left heart failure so that's that side of the heart the left side of the heart thinking particularly about left ventricular failure so what are the causes here well the first ones we have to look at are caused by ski make heart disease so these are all really caused by ischemic heart disease or ihd ischemic disease and this is related to diseases of the coronary arteries now you probably remember that the coronary arteries are the arteries that supply the myocardium itself with blood so the myocardium itself has a high metabolic demand so the first two arteries that leave the aorta are the right and the left coronary arteries to take blood to the heart muscle itself to the myocardium and the problem is that if we think about a cross-section of the arterial wall so this is the lumen in the middle and then we've got the layers of the artery around about the blood should go through the middle here up and down through there through this nice open lumen but what happens is we get the D position over at the Roma at the Roma twist material the code the disease process of atherosclerosis so this at the Roma will accumulate and it tends to develop over the time over time bad diet obesity diabetes smoking then what can happen is we can get a blood clot forming on it that blocks off the artery altogether sometimes or an area of the artery and that will occlude the blood supply to a particular area of the myocardium so we're talking about ischemic heart disease ischemia is reduce blood supply and this is caused by a coronary arterial atherosclerosis causes ischemic heart disease now if an area of the heart muscle loses put supply altogether for example like this if this complete clot that blocks off the whole thing that will cause a myocardial infarction and there'll be death of part of the heart muscle so what that means is that a particular part of the heart muscle will no longer be working properly so there might be an area here then instead of contracting nicely that area dies and doesn't contract that means there's less contractile muscle and that can cause what we call in an a kinetic and a kinetic segment a means without ki-netic is a movement so that area just won't move or can be dyskinetic it won't move properly and that will reduce the pumping efficiency of the left side of the heart another possibility is heart block because of course the heart muscle depends on the coordination of the atrioventricular node sorry the sinoatrial node up here the input is picked up by the atrioventricular node and goes down the conducting pathways and if there's an infarction that involves the conducting pathways then there an area of the conducting pathway dies then the embosses I'm going to get through properly and that can cause a condition called heart block so those first group of causes our complications of ischemic heart disease now another common cause of left ventricular failure is high blood pressure systemic hypertension so for one reason another there's too much constriction in the in the arterial system usually at the level of the arterioles in the systemic arterial system and if the pressure in the systemic arteries is high that means the left ventricle has to work harder to get the blood and the oxygen to the body what we say is that hypertension causes an obligatory an obligatory high output he has to work harder to get the blood through the relatively constricted arterial system where the pressure is higher it makes sense if the pressure here in the arteries are in the air in the Archer as a fairly low then the workload of the left ventricle is also fairly low but if his pumping against a much higher what we call afterload how much higher pressure in the arterial system so there's got to work that much harder to get the blood out and over time that will cause an enlargement of the heart muscle that will cause or what we call a hypertrophy so the hypertension will lead to a hypertrophy the heart will enlarge and this is what causes the cardiomegaly the enlarged heart cardiomegaly and this will compensate for a period of time but eventually this all results in failure so the heart can compensate for a period of time but then as it carries on lodging it it can no longer compensate and we get decompensation and also the very high workload damages the myocardium and we get fibrosis in it so the hypertension will eventually lead to left ventricular failure first they'll be hyper to do with the cardiomegaly but then they'll be failure because of the obligatory high output and the obligatory high workload of the left ventricle myocarditis isn't is another there's another cause Mayo card myocardium itis inflammation of this can be caused by a viral infection the condemned is Thea heart muscle that's one reason why when you've got a violent infection you shouldn't exercise you should rest and cardiomyopathy is basically any disease of the heart muscle cardio heart Mayo muscle pathy disease of so this tends to be a global condition affecting the whole heart muscle and this could be caused by alcohol for example or vitamin B deficiency it's a cardiomyopathy now another group of course these are the valvular diseases now this is the mitral valve here and this is the a aortic valve here so disease of the mitral valve or the aortic valve means that the flow of blood through the heart will not be efficient so for example if there's mitral regurgitation the bloods going to go from the left atrium through to the left hand but then when the left ventricle contracts that valve should shut I should absolutely show it like that so the blood can only get out through the aorta and if that valve is becoming becoming a bit floppy so the ventricle will the atria will contract the put it will go through that valve should shut during ventricular systole but if that's floppy and leaking then we're going to get regurgitation of blood so that when the left ventricle contracts instead of all the blood going into the aorta somes going to go back and obviously that's going to be an inefficient situation all of this disorder of the your tick valve again after contraction this valve should shut so the blood can't get back but if the valve isn't working the blood can get back and again it's inefficient because valves are systems which should ensure one-way flow of blood so disease of the heart valves for example caused by rheumatic heart disease oh the possible infection zone can cause it will mean that the heart is not working efficiently and will be unable to maintain an adequate output to maintain the metabolic demand of the body another cause are abnormal heart rhythms probably the most young said the most common we see is atrial fibrillation so in atrial fibrillation instead of having a nice bordered atrial contraction the atria are just fibrillating and we use the we lose the atrial kick and cardiac output is not as efficient tachycardias tachy dysrhythmias are another course the big pond maitake dysrhythmias is and they don't really allow time for their heart to to fill during diastole so it contracts and then it's contracting again quickly before there's been time for adequate ventricular filling braat braat braat dysrhythmias as well slow slow heart rhythms can also obviously reduce clarity capitis cardiac output his heart rate multiplied by stroke volume another cause of left heart failure is is anemia now anemia is a reduced oxygen carrying capacity of the blood so even if the heart's pumping out normal amounts of blood the normal volumes of blood remember it needs the oxygen doesn't it so there's not enough oxygen going to the to the body that will be detected in the chemoreceptors and that will increase heart rate so people that are anemic have a tantrum of a faster heart rate in the heart working harder to circulate more blood through to try and maintain the oxygen flux it needs to pump a greater volume of blood to get the same amount of oxygen through and and again that causes an obligatory high output it's a bit like the hypertensive situation so anemia is an obligatory high output and again that can lead to enlargement of the heart myocardial hypertrophy cardiomegaly and eventually a left ventricular failure and just a few other things to bear in mind if someone's fluid overloaded we have to be very careful with people with heart disease in hospitals because if we give them too much fluid that will send them into acute pulmonary edema there's a few other causes constrictive pericarditis is a possibility under the the pericardium of course is the layer around the heart or congenital defects ventral septal defect or another one called patent ductus arteriosus the things that people are born with because there hasn't been the appropriate changes and at birth so they're all causes of left ventricular failure and we can actually see left ventricular failure that they tend to be chronic course but we can see it as an acute condition as well so we get an acute left ventricular failure so after a myocardial infarction with large muscle loss seen this a few times unfortunately a lot of the left hander is lost then what happens is the patient goes into acute pulmonary edema because of the backlog of blood through the pulmonary veins as we saw in the last video causing venous congestion blood congestion in the lungs some of the red cells actually get into the alveoli and some of the red cells because the blood is is congesting the lungs in a keep Omni edema some of the red cells getting here and we see pink frothy sputum pink frothy sputum in their in their patients that are extremely distressed an extremely short of breath another a cuckoo causes a acute valve failure I mean there's a complete valve failure then that's the cause of spots the sudden death syndrome the patient will die from that another one is rupture of the intraventricular septum so the can be normally after a myocardial infarction if part of the septum dies that can be a communication between the two sides of the heart with a very poor prognosis there can be obstruction caused by pulmonary embolism so in a forum embolism of the obstruction because then just automatically will be obstruction because of pulmonary arterial branch or a large part of the pulmonary artery is blocked and if it's very severe it can block it off altogether more block off one of the main pulmonary branches going to the right or to the left lung and tamponade is where there is pressure around about the heart pressure round about the heart because that's the pericardium around about there I mean normally blood but potentially fluid gets into the pericardium that's going to constrict the heart so that those acute causes of left ventricular failure as well and as we have said left ventricular failure we all need to right ventricular failure so if this failure of the left ventricle as we noticed in the last video if there's failure in the left ventricle blood is going to be retained in there that means the blood can't get from the left atrium through to the left ventricle easily in the blood dams back now down to the blood back into the pulmonary veins dams the blood back into the lungs that's going to make it harder for the blood to get from the pulmonary artery into the lungs because the lungs are already full of literally congested that's going to make it harder for the blood to get from the right ventricle through into the pulmonary artery that's going to increase the workload of the right ventricle and the same thing happens initially a compensate you get a right ventricular hypertrophy and compensation but then as the hypertrophic continues the heart enlarges we at this cardiomegaly situation then eventually there's going to be a right ventricular failure so what we see is left ventricular failure will lead to right ventricular failure or overtime and in the next video we'll look specifically at the causes where the failure begins in the right ventricle but that was the heart failure etiology in starting off with left ventricular failure

Channel: Dr. John Campbell

Views: 98,895

Keywords: heart, heart failure, LVF, left ventricular failure, heart disease, pathophysiology, medical education, nurse education, causes, aetiology, etiology, disease

Id: sFxLIfM-yDo

Length: 18min 33sec (1113 seconds)

Published: Mon Feb 18 2019